1. Field of the Invention
The present invention relates to a method of getting an energy level of a communication channel.
2. Description of the Related Art
In recent times, as a communication technique is developed, various types of wireless communications are widely used in real lives.
In such a wireless communication technique, world standards are established in various fields such as mobile phones, wireless LANs, Bluetooth, Zigbee, and so on, and used in optimal fields according to characteristics thereof.
Here, Zigbee is referred to as one of IEEE 802.15.4 Standards, which support local area communication, and is utilized in various fields such as intelligence home networks, local area communication markets such as buildings, industrial instrument automation, distribution, environment monitoring, human interface, telematics, military fields, and so on.
In a Zigbee network, a size of equipment is relatively small and its power consumption is relatively low. In addition, since manufacturing cost of the equipment used in Zigbee networking is low in comparison with another networking, a ubiquitous construction solution such as a home network is in the spotlight in recent times.
Meanwhile, a personal area network (PAN) coordinator for constructing the Zigbee network must perform a process of selecting a radio frequency channel, which is to be used in a PAN thereof.
A frequency channel selected for network construction by the PAN coordinator is referred to as a logical channel.
While the logical channel may be determined by a predetermined value, more preferably, another PAN coordinator may search a channel, which is not used, for oneself.
For this, the PAN coordinator generally performs energy detection (ED) scanning of sixteen channels.
In IEEE 802.15.4 Standards, even when a wireless LAN (WLAN) is detected, all of the sixteen channels must be scanned.
FIG. 1 is a view for explaining a channel relationship between a WLAN network (802.11) and a Zigbee network (802.15.4).
Referring to FIG. 1, according to a conventional technique, a PAN coordinator performs EDD scanning of all the sixteen channels from a channel CH1 of 2405 MHz band to a channel CH16 of 2480 MHz band.
Here, FIG. 1 is illustrated under the assumption that the WLAN uses the channel of 2412 MHz band, and as shown in FIG. 1, a bandwidth of one channel in the WLAN network is similar to a sum of four bandwidths in the IEEE 802.15.4 network.
When the WLAN use the channel of 2412 MHz band, the PAN coordinator cannot use channels of 2405, 2401, 2415 and 2420 MHz bands.
However, according to the conventional art, when the PAN coordinator detects a WLAN signal in the 2405 MHz band through the ED scanning, ED scanning of all the channels of 2401, 2415 and 2420 MHz bands had to be performed.
Here, since a process of performing ED canning of one channel consumes much time, unnecessary ED scanning of all the channels in the conventional art may cause unnecessary time consumption upon establishment of the Zigbee network.
Meanwhile, Patent Document 1 discloses a channel change determination mechanism of a WLAN. A technique disclosed in Patent Document 1 also sequentially performs ED scanning to construct a network in a state in which energy levels are stored according to channels. However, when problems such as crosstalk and delay occur, the channel is merely replaced with another channel, and inefficiency of the ED scanning due to overlapping of the WLAN is remained as it is.